EXPOSING THE SCREEN
Exposing Monocolor Screens for Printing on Paper or Textile
After the screen is thoroughly dry, it is ready for exposure. For home use, one of the easiest ways to expose a screen is to have the bulb or light source placed under the screen and beamed upward toward the artwork (See diagram). What is needed is a tight sandwich between the screen and artwork. Place the artwork on the cleaned glass and center the screen on top of the artwork. Use a piece of black construction paper or something similar to cover the inside of the screen.
Now place a book on top of the paper. The screen fabric and the artwork are pressed against the glass by the book or similar weight. This is to prevent the light from creeping to areas where it is not wanted, and will give you a sharply detailed screen. Please follow the order of the materials exactly as shown for best results.
There is an important relationship between how well your screen develops and: (1) The time of exposure; (2) The bulb wattage; (3) The distance between the light source and the screen.
The time of exposure depends upon bulb wattage and the distance between the light source and the screen. Screen sizes 8” x 10” and 10” x 14”, placed 12” away from a 150W flood bulb, will cause exposure time to vary from 4 to 6 minutes. Screen size 12” x 16” may need increased distance from the light source to ensure full image exposure. This increase in distance from 12” to
20” will require longer exposure time. Try exposing the screen about 6 to 8 minutes. According to the opacity and line quality of your artwork, you will need to experiment with this formula; however, the following is an approximate relationship. When using a 150W flood bulb, try exposing the screen for about 20 seconds per inch distance between the screen and light source.
For screens larger than 14” x 17” this formula may not work. You may even need multiple bulbs to get an even dispersing of light. Caution: Prolonged exposure to light when shooting the screen may result in an overexposed screen which will not wash out during development. Overexposure can also burn the stencil. If the light is too close it may expose the center only and not the outer edges.
Exposing Multicolor Screens for Printing on Paper
The screens are registered by taping registration pins to the glass that you are exposing the screens on, and placing your artwork on the pins. Center the screen over the artwork and make an L shape and an inverted L shape at the bottom corners of the screen with tape. Each successive color is then placed on the registration pins, centered in the screen within the L guides, and exposed (See Diagram).
Exposing Multicolor Screens for Printing on Textiles.
If you have a professional “T” shirt printing machine, expose the screens the same as for printing on paper. If you are using the homemade Eye-Bolt, L-Angle system the screens must be prepared in a special way. Each screen must have 2 Eye-Bolts screwed halfway into the top of the wood frame. Half of the threads should be visible. This will give you room for adjustments when printing. Each screen must also have an L-Angle screwed on the frame at the top (See Diagram).
Tape a piece of wood the same thickness as the screen, on the exposure glass. Screw a bolt into the center of the wood (See Diagram) so the L-Angle can lock up against it. The 2 Eye-Bolts should butt against the wood and the L-Angle must butt against the bolt creating a 3 point contact (See Diagram). Place the screen on the glass in this 3 contact point position. Place your artwork in the center of the screen and tape the registration pins down so all the following
acetates will be in the same place. Now expose the screen to the light source. When exposure is complete, remove the first acetate and place the next acetate on the registration pins. Place the screen on the artwork
in the 3 contact point position as was done for the first screen. Expose the next screen. Continue this process until all screens are exposed. With this 3 point contact system, all the screens will be exposed in registration and this will make printing much easier for you.
Important Things to Remember
Minimum starting distance should be 12” from artwork to light source. Due to different fabric meshes and line widths of artwork, you may have to experiment with this formula; make modifications as necessary.
If you do not use a bulb holder, but rather an ordinary household lamp, the light will be more diffuse, and you may need more exposure time.
DEVELOPING THE SCREEN
Work in a dim or amber light.
Develop the screen immediately after exposure. After exposing the screen, the image is developed by washing the screen with cool water. Light to moderate pressure is best and can be obtained by using a shower or garden hose with a sprinkler nozzle. All opaque areas that were in your artwork should wash out and your image will become a direct stencil or part of the screen. Remember: In the open areas where the photo emulsion does not harden, the ink will pass through the mesh, like a strainer, and onto your paper, textile or other substrate.
Prop the screen up and move the hose from side to side or in a circular motion beginning with the outside of the screen. Turn frequently and
wash out both sides. When the image begins to wash out you can turn the regular lights back on.
Hold the screen up to the light and check to see if light shines clearly and evenly through the areas that were opaque. If so, then all areas washed out; if not then gently wash again. Be careful, too much washing can soften the emulsion and it may begin to break away in areas that are necessary to define your design.
If the screen washes out quickly and begins to wash away it could be underexposed; you may need to increase the exposure time. If the areas that were opaqued will not wash out, the screen could be overexposed. In that case you may need to reduce the exposure time or make your artwork more opaque.
After your screen is dry, tiny pinholes or starlike specks may appear when you hold the screen up to the light. With a paint brush, dab some excess sensitized photo emulsion onto these pinholes. You can also pain the emulsion in areas that you wish to close or better define. Do not wash the screen after you have touched up with sensitized emulsion. Simply place the screen under and ordinary lamp or sunlight to dry.
Blockouts work best for closing unwanted open areas in the screen. With blockouts you can close certain areas in the screen, and print; then you can remove the blockout, and reverse the process, so the areas that did not print will now print, and the areas that did print will not print.
Exposing Monocolor Screens for Printing on Paper or Textile
After the screen is thoroughly dry, it is ready for exposure. For home use, one of the easiest ways to expose a screen is to have the bulb or light source placed under the screen and beamed upward toward the artwork (See diagram). What is needed is a tight sandwich between the screen and artwork. Place the artwork on the cleaned glass and center the screen on top of the artwork. Use a piece of black construction paper or something similar to cover the inside of the screen.
Now place a book on top of the paper. The screen fabric and the artwork are pressed against the glass by the book or similar weight. This is to prevent the light from creeping to areas where it is not wanted, and will give you a sharply detailed screen. Please follow the order of the materials exactly as shown for best results.
There is an important relationship between how well your screen develops and: (1) The time of exposure; (2) The bulb wattage; (3) The distance between the light source and the screen.
The time of exposure depends upon bulb wattage and the distance between the light source and the screen. Screen sizes 8” x 10” and 10” x 14”, placed 12” away from a 150W flood bulb, will cause exposure time to vary from 4 to 6 minutes. Screen size 12” x 16” may need increased distance from the light source to ensure full image exposure. This increase in distance from 12” to
20” will require longer exposure time. Try exposing the screen about 6 to 8 minutes. According to the opacity and line quality of your artwork, you will need to experiment with this formula; however, the following is an approximate relationship. When using a 150W flood bulb, try exposing the screen for about 20 seconds per inch distance between the screen and light source.
For screens larger than 14” x 17” this formula may not work. You may even need multiple bulbs to get an even dispersing of light. Caution: Prolonged exposure to light when shooting the screen may result in an overexposed screen which will not wash out during development. Overexposure can also burn the stencil. If the light is too close it may expose the center only and not the outer edges.
Exposing Multicolor Screens for Printing on Paper
The screens are registered by taping registration pins to the glass that you are exposing the screens on, and placing your artwork on the pins. Center the screen over the artwork and make an L shape and an inverted L shape at the bottom corners of the screen with tape. Each successive color is then placed on the registration pins, centered in the screen within the L guides, and exposed (See Diagram).
Exposing Multicolor Screens for Printing on Textiles.
If you have a professional “T” shirt printing machine, expose the screens the same as for printing on paper. If you are using the homemade Eye-Bolt, L-Angle system the screens must be prepared in a special way. Each screen must have 2 Eye-Bolts screwed halfway into the top of the wood frame. Half of the threads should be visible. This will give you room for adjustments when printing. Each screen must also have an L-Angle screwed on the frame at the top (See Diagram).
Tape a piece of wood the same thickness as the screen, on the exposure glass. Screw a bolt into the center of the wood (See Diagram) so the L-Angle can lock up against it. The 2 Eye-Bolts should butt against the wood and the L-Angle must butt against the bolt creating a 3 point contact (See Diagram). Place the screen on the glass in this 3 contact point position. Place your artwork in the center of the screen and tape the registration pins down so all the following
acetates will be in the same place. Now expose the screen to the light source. When exposure is complete, remove the first acetate and place the next acetate on the registration pins. Place the screen on the artwork
in the 3 contact point position as was done for the first screen. Expose the next screen. Continue this process until all screens are exposed. With this 3 point contact system, all the screens will be exposed in registration and this will make printing much easier for you.
Important Things to Remember
Minimum starting distance should be 12” from artwork to light source. Due to different fabric meshes and line widths of artwork, you may have to experiment with this formula; make modifications as necessary.
If you do not use a bulb holder, but rather an ordinary household lamp, the light will be more diffuse, and you may need more exposure time.
DEVELOPING THE SCREEN
Work in a dim or amber light.
Develop the screen immediately after exposure. After exposing the screen, the image is developed by washing the screen with cool water. Light to moderate pressure is best and can be obtained by using a shower or garden hose with a sprinkler nozzle. All opaque areas that were in your artwork should wash out and your image will become a direct stencil or part of the screen. Remember: In the open areas where the photo emulsion does not harden, the ink will pass through the mesh, like a strainer, and onto your paper, textile or other substrate.
Prop the screen up and move the hose from side to side or in a circular motion beginning with the outside of the screen. Turn frequently and
wash out both sides. When the image begins to wash out you can turn the regular lights back on.
Hold the screen up to the light and check to see if light shines clearly and evenly through the areas that were opaque. If so, then all areas washed out; if not then gently wash again. Be careful, too much washing can soften the emulsion and it may begin to break away in areas that are necessary to define your design.
If the screen washes out quickly and begins to wash away it could be underexposed; you may need to increase the exposure time. If the areas that were opaqued will not wash out, the screen could be overexposed. In that case you may need to reduce the exposure time or make your artwork more opaque.
After your screen is dry, tiny pinholes or starlike specks may appear when you hold the screen up to the light. With a paint brush, dab some excess sensitized photo emulsion onto these pinholes. You can also pain the emulsion in areas that you wish to close or better define. Do not wash the screen after you have touched up with sensitized emulsion. Simply place the screen under and ordinary lamp or sunlight to dry.
Blockouts work best for closing unwanted open areas in the screen. With blockouts you can close certain areas in the screen, and print; then you can remove the blockout, and reverse the process, so the areas that did not print will now print, and the areas that did print will not print.
0 comments:
Post a Comment